Scilab Function
Last update : 12/1/2004

iirlp - Lp IIR filter optimization

### Calling Sequence

  `[cost,grad,ind]=iirlp(x,ind,p,[flag],lambda,omega,ad,wa,td,wt)`

### Parameters

- `x`: 1X2 vector of the module and argument of the poles and the zeros of the filters
- `flag`: string : `'a'` for amplitude, 'gd' for group delay; default case for amplitude and group delay.
- `omega`: frequencies where the filter specifications are given
- `wa,wt`: weighting functions for the amplitude and the group delay
- `lambda`: weighting (with `1-lambda`) of the costs (`'a'` and `'gd'` for getting the global cost.
- `ad, td`: desired amplitude and group delay
- `cost, grad`: criterium and gradient values

### Description

optimization of IIR filters for the Lp criterium for the amplitude and/or the group delay. (Rabiner & Gold pp270-273).